Hormesis vs ALARA at the Adelaide Radiology Centre

Dr. Madhava Bhat authored the piece below in 2010. The article was published in the journal of the Australasian College of Physical Scientists and Engineers in Medicine. (source as above). I am quoting only part of Dr. Bhat’s article. The full article is available at the above link. (The National Library of Australia gives the ISSN of the journal as 0158-9938 and the Libraries Australia ID as 54273745. Springer gives the date of publication of the relevant issue of the journal as September 2010)

Quote: “My own experience illustrates that even professional radiation physicists are not spared from radiation phobia. On one occasion I was working near the door of a high dose rate (HDR) brachytherapy room, where the dose rate out of the shielding container is typically 5 uSv/h. My colleague, a physicist, insisted that I move away from that area as they considered the area to be characterized by a ‘high radiation level’. I obliged, as at the time, it was easier than to explain why it was safe for me to work there.

I was born in Kerala where the natural background radiation level is as high as 4 lGy per hour. I was continuously exposed at this dose rate until the age of 24 when I relocated to a different place. HDR treatment exposure has a typical duration of about 5 min and my presence for the duration of the patient treatment would have lead to an exposure of 0.3 lSv above natural background radiation. If I had attended 100 such procedures in a year my total dose would be 30 lSv. This small occupational radiation dose is well within fluctuations observed in the background radiation level often a result of sunspot activity and cosmic ray intensity. Furthermore this level of exposure represents less than 0.2% of the maximum annual dose limit prescribed for a radiation worker by the statutory radiation protection authority.

Current ionising radiation protection standards are based on the simple Linear-No-Threshold (LNT) hypothesis. The LNT hypothesis states that the dose–response relationship through all bands is linear and that there is no safe threshold level of exposure. The LNT hypothesis was developed on the basis of an extrapolation of our knowledge of pathology at high doses of radiation; e.g. high dose exposure to early radiation workers, impacts of exposure on the survivors of the Hiroshima and Nagasaki atom bomb. It is important to note that the LNT hypothesis is not based on any scientific data at low levels of radiation exposure. I therefore consider the adoption of this model for radiation protection to be based on illegitimate grounds.” end partial quote.

I was trained in basic radiological safety by the Australian Army in the 1970s. At that time I was taught that keeping a work environment clean was most important. To this end I was trained to use PDR27a gamma/beta detectors and scintillator detectors. I used a scintillator every afternoon in order to check for isolated spots of contamination caused by faulty seals on radium containers, and other sources of contamination. It was important to identify and resolve any accidental contamination no matter how small. The concept of ALARA , which keeps exposures as low as reasonably possible, guides everything from dental exposures to OH&S for astronauts. As well as the health and safety of staff and patients at the Adelaide Radiology Centre.

It worries me that a skilled radiologist is challenging Australia’s nuclear safety regime (based upon ALARA, which Dr. Bhat considers to be “based on illegitimate grounds”). The implication I gain is that his place of birth of Kerala, India, with it’s high natural rate of background radiation of “as high as 4 lGy per hour” (Dr. Bhat, as above), imposes no health risk at all to the people who live their entire lives there. Having been a radiation worker, and happy in the job, I’ll let the reader decide if adherance to Workplace OH&S wilingly and happily makes me the radiophobe Dr Bhat’s article implies I am, along with his supposedly equally timid coworkers.

I wondered if I could verify the thought that the Naturally High Background Radiation of Kerala, India has produced any reliable health statistics which showed either a health benefit from living there, or a health risk from living there or both. (Differing disease responses to the environment.) I wondered in particular, given that cancer occurs in every human population, whether living in Kerala, India, produced cancers which became radio-resistant and chemo-therapy resistant either more often and/or earlier in the treatment regime. (The radio-resistance of cancer due to treatment is a widely reported event. Whereas the patient in such a situation becomes sicker and sicker from each subsequent treatment, implying normal cells do not adapt well to radiation therapy in the setting of cancer treatment, in my observation, as a layman.)

I have completed a cursory search for the health statistics for Kerala, India, as follows:

BOTH point mutations and structural aberrations of chromosomes are induced by ionising radiations, causing genetic variation and abnormalities in man and other organisms. The mutagenic effects are dose dependent and in Drosophila a linear relationship between dose and mutation rate has been shown for doses up to 5 R (ref. 1). Although man accumulates approximately 5 R of radiation from the environment in 30 yr of reproductive life, it is not known whether this is of any radio-biological consequence2. Nor is it known whether in man there is a threshold phenomenon at low doses (several hundred or thousand mr. per year), although there is greater repair of mutational or pre-mutational damage after low-dose irradiation3. In a coastal area of Kerala, South India, the background radiation is 1,500–3,000 mr. Yr−1 due to the presence of thorium-containing monazite mineral in the soil4–7 (Fig.1). A survey of the rat population in this area with respect to several measurable and non-measurable traits and of humans with regard to dermatoglyphics and demographic data such as fertility index, sex ratio and infant mortality rate revealed no mutational effects4,7,8. During an epidemiological study of nodular lesions of the thyroid in this area9, we noticed an apparently high prevalence of Down’s syndrome and other forms of severe mental retardation10. We therefore made a house-to-house survey of developmental abnormalities in this area and in a comparable control area without high background radiation7 (Fig. 1). We also determined the frequency of chromosome aberrations in a sample of the normal population living in the study and control areas. The observations we report here support the view that radiation-induced genetic anomalies occur with above average frequency in the population living in the area with high background radiation. The area surveyed was the southernmost one-fifth of the Chavara-Neendakara strip (Fig. 1). In the thatched huts which constitute 75% of all households, the exposure risk is 1,500–3,000 mr. Yr−1, and personal exposure, as measured by calcium fluoride dosimeters, closely parallels the exposure risk in the households. The control area consisted of the Purakkade–Punnapura villages, with a background radiation of approximately 100 mr. yr−1 (ref. 7). Households were visited repeatedly to ensure examination of all members. Only gross abnormalities evident on clinical examination were recorded. Cytogenetic abnormalities were scored blind on slides prepared from 64-h micro-blood cultures11. ” End Quote.

Quote: “RESULTS: Out of 4271 deaths recorded during 5 years, diseases of the circulatory system contributed 40%. Coronary heart disease was the leading cause of death in men (31.1%) and women (17.6%). Age-standardized cardiovascular disease (CVD) death rates were 490 for men and 231 for women per 100,000 person years. CONCLUSION: The burden of CVD deaths in this community now exceeds that of industrialized countries.” end quote.

Quote: “3.6.8 The percentage share of Neoplasms deaths is highest 12.0 per cent in case of
medically certified deaths reported from Kerala. The share of this major group in case of Bihar,
which has reported the lowest are 0.2 per cent in respective State’s total medical certification
of death”.

Quote: “Abstract. The coastal belt of Karunagappally, Kerala, India, is known for high background radiation (HBR) from thorium-containing monazite sand. In coastal panchayats, median outdoor radiation levels are more than 4 mGy y-1 and, in certain locations on the coast, it is as high as 70 mGy y-1. Although HBR has been repeatedly shown to increase the frequency of chromosome aberrations in the circulating lymphocytes of exposed persons, its carcinogenic effect is still unproven. A cohort of all 385,103 residents in Karunagappally was established in the 1990’s to evaluate health effects of HBR. Based on radiation level measurements, a radiation subcohort consisting of 173,067 residents was chosen. Cancer incidence in this subcohort aged 30-84 y (N = 69,958) was analyzed. Cumulative radiation dose for each individual was estimated based on outdoor and indoor dosimetry of each household, taking into account sex- and age-specific house occupancy factors. Following 69,958 residents for 10.5 years on average, 736,586 person-years of observation were accumulated and 1,379 cancer cases including 30 cases of leukemia were identified by the end of 2005. Poisson regression analysis of cohort data, stratified by sex, attained age, follow-up interval, socio-demographic factors and bidi smoking, showed no excess cancer risk from exposure to terrestrial gamma radiation. The excess relative risk of cancer excluding leukemia was estimated to be -0.13 Gy-1 (95% CI: -0.58, 0.46). In site-specific analysis, no cancer site was significantly related to cumulative radiation dose. Leukemia was not significantly related to HBR, either. Although the statistical power of the study might not be adequate due to the low dose, our cancer incidence study, together with previously reported cancer mortality studies in the HBR area of Yangjiang, China, suggests it is unlikely that estimates of risk at low doses are substantially greater than currently believed. The risk of cancer from natural background ionizing radiation. [Health Phys. 2009] PMID:19066487 [PubMed – indexed for MEDLINE]” end quote.

Conclusion: I find that contrary to the assertions made by Dr. Bhat and others, that the nuclear regulatory protection regime is not illegitimate, that Dr. Bhat ignores reporting the risks present in his original home place of Kelara, India, and that authoritative sources, including the Indian government finds that Kelara, India suffers the highest number of cancer death reports in the whole of India. Further, other radiation related diseases such as Down’s Syndrome and Heart Disease impact upon the population of Kelara, India and that Heart Disease rates in Kelara, India “now exceeds heart disease rates found in the industrialised world”.

Contrary to Dr. Bhat’s view, if I lived in Kelara, India from birth, and had access to open information well known to the government of India and to everyone in fact, I would consider moving to Adelaide South Australia.